What failing grout looks like

Grout that is cracking, crumbling, or pulling away from tile edges is no longer doing its job. Discoloration alone — dark staining from mold or mineral deposits — is a surface problem. Structural failure, where the grout has receded below the tile surface or is missing in sections, is the condition that allows water to reach the substrate.

The case for regrouting before it gets worse

Once water moves under tile, it reaches the cement board or drywall behind the surround. In a shower, that moisture sits for hours after each use. The result is mold in the wall cavity, substrate failure, and eventually tile that moves when touched. Regrouting when the grout first shows structural failure is a fraction of the cost of addressing what follows.

Regrout vs. tile replacement

If the tile itself is sound — no cracks, no hollow spots when tapped, no movement — regrouting extends the installation's life significantly. If tile has cracked or the bond to the substrate has failed, replacing the affected tiles before regrouting is the right sequence. Installing new grout over moving tile produces the same failure within a year.

What the process involves

Regrouting requires removing the old material, which is done with a grout saw or oscillating tool to avoid damaging the tile edges. The joints are cleaned and allowed to dry before new grout is applied in thin passes and tooled to match the original profile. Color matching is approximate — most homeowners find a close match acceptable in a bathroom used daily.